棉兰老流年代际变异和长期趋势的特征及机理

The low-latitude western boundary current of the Pacific Ocean plays an important role in the heat budget of the warm pool, large-scale energy transport, and climate variability of the tropical and global ocean. The Mindanao current (MC) splits at the Philippine sea and fits the Indonesian Throughflow (ITF) and the North Equatorial Countercurrent (NECC), and is involved in the global thermohaline circulation. The MC regulates the distributions of the momentum, mass, heat of the tropical Ocean and plays a vital role in the tropical climate variability. Previous studies were mainly focused on the seasonal to interannual variations of the MC. However, decadal and long-term variation of the MC and their mechanisms are still unclear. This project intends to combine the analysis of observational data, the reanalysis data, the model output and model experiments with a reduced-gravity model to investigate decadal variability and long-term trend of the MC. Here we focus on the three scientific issues: (1) characteristics and mechanisms of the decadal variability of the MC; (2) the long-term change of the MC under the changing climate; (3) the influence of MC's variation on ITF and NECC. This project is expected to improve our understanding the regional ocean dynamics and climate variability of the western tropical Pacific Ocean and helpful for advancing the simulation and prediction of climate models.

太平洋低纬度西边界流对暖池热盐收支、大尺度能量交换、热带及全球气候变化具有至关重要的作用。其中，位于菲律宾海的棉兰老流（MC）是印尼贯穿流（ITF）和北赤道逆流（NECC）的主要水源，是大洋经圈翻转环流的重要组成部分。MC在调控热带太平洋和印度洋海洋、气候变化之中起到关键作用。以往研究大多集中在MC的季节-年际变异，而对MC的年代和长期变异研究较少，对该时间尺度的变异机理缺乏足够的认识。本项目基于对观测资料、再分析资料、高分辨率模式资料的分析和约化重力模式实验，研究MC的年代变异及长期趋势，重点探讨：（1）MC年代变异的时空特征与机理、（2）在气候变化背景下MC的长期变化趋势及影响因素、（3）MC变化对ITF和NECC动力学及热力学影响三个科学问题。本课题的研究工作，能够加深我们对热带西太平洋海洋环流动力学和气候变化的理解，并有助于提高海气耦合模式对西太平洋的模拟和预报能力。

太平洋低纬度西边界流对暖池热盐收支、大尺度能量交换、热带及全球气候变化具有重要影响。其中，棉兰老流（MC）作为印尼贯穿流（ITF）和北赤道逆流（NECC）的主要水源，是大洋经圈翻转环流的重要组成部分，在调控热带太平洋和印度洋海洋、气候变化之中起到关键作用。然而，以往研究多关注MC的高频变异，对其年代和长期变异等低频变异的特征和机理研究不足。本项目基于多种观测、再分析、高分辨率模式资料和约化重力模式实验，以MC的低频变异为主要研究对象，揭示了MC的年代际及多年代际长期趋势的变异特征及物理机制；理清了厄尔尼诺事件对MC的调制影响及机理；进一步，将视野扩展到临近的印度洋，揭示了印度洋偶极子对热带西太平洋的显著调制影响。总体上，本项目的工作加深了学界对热带西太平洋海洋环流动力学和气候变化的理解，有助于提高海气耦合模式对西太平洋的模拟和预报能力。